[lecture] Add a lecture on solving OLS using Math and Matrix Algebra

[mmcky]

@mmcky to write a first draft lecture on OLS using math and Matrix Algebra

[mmcky]

@HumphreyYang I am tied up with a few things this afternoon but if you wanted to add a few of the ideas around Fisher that was discussed this morning for OLS the notebook is in:

Dropbox/QuantEcon Writing Hackathon (Jan 2023)/mmcky/

Please feel free to add as you see fit.

[mmcky]

This is a pretty nice review

https://towardsdatascience.com/a-look-at-the-maths-behind-linear-regression-e9616ca0598

[mmcky]

How much of the mathematical properties should we include

https://en.wikipedia.org/wiki/Simple_linear_regression

[mmcky]

This is done in https://github.com/QuantEcon/lecture-python-intro/blob/main/lectures/simple_linear_regression.md